At present, an existing in-cell touch screen detects a touch position of a finger on a principle of mutual capacitance or self capacitance. Therein, the touch screen on the principle of self capacitance may comprise a plurality of self-capacitance electrodes, which are disposed in a same layer and insulated from each other, disposed therein; when the human body does not touch the screen, a capacitance of each of the self-capacitance electrodes is a fixed value; when the human body touches the screen, the capacitance of the corresponding self-capacitance electrode is the fixed value superimposed with the human body capacitance, and a touch detecting chip can judge the touch position in a touch period by detecting variation of capacitance value of each of the self-capacitance electrodes. Since the human body capacitance may act on all of the self capacitances, as compared with a case that the human body capacitance may only act on a projected capacitance in the mutual capacitance, a touch variation amount caused by the human body touching the screen will be greater than that of the touch screen fabricated on the principle of mutual capacitance, and thus, as compared with the touch screen of the mutual capacitance, the touch screen on the principle of self capacitance can effectively improve a signal to noise ratio of the touch, so as to improve accuracy of touch sensing.
When the touch screen is designed on the principle of self capacitance, each self-capacitance electrode needs to be connected with a touch detecting chip through a individual lead, and as show in FIG. 1, each lead may include: a conducting line 2 which connects a self-capacitance electrode 1 to a frame of the touch screen, and a periphery wiring 4 disposed at the frame of the touch screen which couples the self-capacitance electrode 1 to a connecting terminal 3 of the touch detecting chip.
Since the number of the self-capacitance electrodes is very large, the number of the corresponding leads will also be very large; with a case that an area of each self-capacitance electrode is 5 mm*5 mm as an example, a 5-inch liquid crystal display screen needs 264 self-capacitance electrodes; and if each self-capacitance electrode is designed to be smaller, there will be more self-capacitance electrodes, then it is necessary to provide more leads. When being designed, in order to reduce the number of film layers, the conducting lines in the leads and the self-capacitance electrodes are typically disposed in a same layer; more conducting lines will result in a larger touch dead zone, which refers to a region where wiring lines are concentrated in the touch screen; in this touch dead zone, signals are relatively more disordered, and thus, it is referred to as the touch dead zone, that is, touch performance within the region cannot be guaranteed. FIG. 1 is illustrated with 30 self-capacitance electrodes as an example, the 30 self-capacitance electrodes need 30 conducting lines to connect them to the frame, and 10 conducting lines are needed in a region where the conducting lines are densest, which will result in a larger touch dead zone.
In addition, since the number of the conducting lines is larger, the number of the periphery wirings disposed at the frame and corresponding to the conducting lines in a one-to-one relationship correspondence is also larger, which will cause expansion of the frame of the touch screen, and is not conducive to narrow frame design.
Thus, it is necessary to reduce the number of the leads of the self-capacitance electrodes in the touch screen, under a circumstance that a distribution density of the self-capacitance electrodes in the touch screen is ensured, so as to implement the narrow frame design.